Determination of the Neutron Temperature at the Center of the Thermal Test Reactor

The effective temperature of the thermal neutrons at the center of the internal column of the Thermal Test Reactor has been measured by means of a danger coefficient technique. Assuming that the thermal neutrons have a Maxwellian velocity distribution, the experiments indicated that the TTR neutrons have a Kelvin temperature of 300°. The unique relation which exists between a 1/v and a non 1/v neutron absorber for neutron capture as a function of energy is the underlying principle upon which the experimental technique is based. The physical temperature of the reactor during the period of experimentation was also measured as 300°K.